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LAB 12 Direct Radiator

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rbarone View Drop Down
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    Posted: 01 April 2018 at 2:16pm
I'm checking out the performance spec's from Eminence for a LAB 12 4ohm in a simple 2.874 square foot vented box - which can be built from half a sheet of plywood.

If these are accurate, is there enough to be gained by building a bigger/heavier folded horn?

looking forward to some experienced folks weighing in for advice.  thx


http://www.eminence.com/pdf/LAB_12C_cab.pdf


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2018 at 2:43pm
Depends what you're trying to achieve. Folded horn loading will give a huge boost in efficiency for the Lab 12, as it's direct radiator efficiency is quite low, but you can achieve excellent results if you want a smaller box that'll play low and be used in singles. There was a recent thread about Art Welter's design for 2x Lab 12's in reflex, but as it turned out there was a preferable option for the same enclosure using a BMS woofer, so I wouldn't say the Lab12 is optimal even for that sort of small box reflex sub design, but if you've got them laying around they will certainly do. 

If you're building Lab 12 horns you'll be looking at stacks of 6 cabinets to play low with a smooth response, but if you're doing large gigs with extreme SPL requirements, and you regularly use stacks of 6 (4 in a pinch if you mostly play indoors) then horn loading is the way to go. If not, probably reflex but you can also look at tapped horns or bandpass as a halfway house solution.


Edited by Hemisphere - 01 April 2018 at 2:46pm
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rbarone View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rbarone Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2018 at 3:30pm
thx hemisphere for shedding some light.

to add a bit more info, i'd use just a pair to hold up the bottom of a pub-sized p.a. <200 people.  

small footprints are always helpful; it's mobile, so light weight is good too... 

i've built a few different subs, but never a tapped horn, so i'm curious.  as a woodworker, i think i'd also enjoy the build.

I've read a lot about the tham family & some about jbell's similar design.  when i began reading up on the lab sub, i wondered if the gains over the vented box were justified.

i've got plenty of class d power for a pair, so i guess efficiency may not be the most important factor at this small scale.

once again, thanks for sharing your time & experience



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2018 at 4:20pm
No point in building two Lab subs (or it would be one actually, if you only have two drivers), but even with small gigs you'll still find your bass section lacking with a pair of 89dB reflex subs.

Some discussion on Lab12 suitable tapped horn designs here: http://www.diyaudio.com/forums/subwoofers/264766-pair-lab12s-recommendations.html


That'll really hit the low notes, and although it is excursion limited to about 120-124B peak SPL, you've got plenty of wiggle room in the 60-80Hz region to boost the bass a few dB in the regions where it's most prominent in music program.

Here's the thread on Art Welter's Dual Lab12 design: https://forum.speakerplans.com/arts-dual-lab-12_topic99080.html

A single lab12 in an 80 litre enclosure is going to max out at just 113dB, so about half as loud as it would go in a PAL12 with similar frequency extension.

As I mentioned in that thread, the driver you really want for this sort of design is a BMS 12s305, that'll achieve 122dB, about as much as the PAL12 tapped horn with comparable frequency response in a considerably smaller box, provided you have enough Watts to drive it. Driver is about the same price in the UK but for you it'll be more.

User 'doller' on this forum has built a bunch of Art Welter's dual Lab12 reflex design so you should talk with him - maybe his applications are similar enough to yours that you can get precise advice on how many Lab 12 reflex bins you'd need to build.


Edited by Hemisphere - 01 April 2018 at 4:23pm
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rbarone View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rbarone Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2018 at 5:01pm
thank you very much - really intriguing stuff.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2018 at 8:07pm
cookie dj's tham 12 rig

Read this too. I really like this setup and may copy it for a second room rig. It clearly punches above its compact size!

Could also build some compact 15s?

You need decide what your goal is. How low do you need to go, how loud and how small?

Striking this balance to meet your needs is the hard bit.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rbarone Quote  Post ReplyReply Direct Link To This Post Posted: 01 April 2018 at 8:50pm
wow..  that's a cool small rig.  i dig it.

the tham's are designed around speakers that are rare in the u.s.  i'd be inclined to experiment with a pair if i found a suitable replacement.

eminence speakers abound over here, & i also have a wholesale account that makes them very affordable.

i do have access to this sica - the spec's are close..  are they close enough?  i don't know.  

uploads/3467/p-a-s12k3_2018-04-01_20-45-59.pdf




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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2018 at 10:34am
tham 12 on sp

Info on it here.

Martinsson the designer has posted all the info on the cabinet so you can model it in the free software hornresp. Yes you'll have to do some legwork but its a free plan!

Mr martinsson also says in this thread there are some drivers simmed on his thread... link for that inn the first post of the thread I've linked to.

If this floats your boat you could also look at the tham 15, the jbell ss15 and mth30. Again, hit Google and see if they appeal.


Edited by JonB67 - 02 April 2018 at 10:35am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doller Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2018 at 11:02am
If you arn't putting labs in a lab horn the impedence is a pain in the arse. You will need a good solid amp to drive them. You can be hitting 2 to 3 ohms. I would go with the BMS if I could. Luckly I do have amps that will drive them. just a thought.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rbarone Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2018 at 1:01pm
very true...  i haven't been able to find hornresp for a mac.  is it available?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2018 at 2:38pm
No, but it's very lightweight so you can easily run it in a virtual machine (I mean, as easy as it is to run anything in a virtual machine!)

I should point out that my advice about the Labs and BMS driver only really applies if you're constrained to a particular box design or driver choice - the THAM12 is an excellent option for a compact, lightweight rig that will go loud, but you will sacrifice a little sound quality over a straight reflex system (subjectively speaking and genre dependent of course, but reflex is going to be the best all rounder for the widest variety of audience tastes and genres).

From Martinsson's page, the Tham12 can achieve around 132dB with some drivers, which for the box size is just nuts. Literally four times as loud as your original design idea (not the equivalent of four boxes - actually equivalent of about eight boxes), and although you won't get much below 50Hz at that level, you can still achieve 120dB at 40Hz.

That said, if true sub bass is something you and your audience will really appreciate, the BMS 12s305 in the Art Welter box can really excel. With enough amp power and a limiter, the dual 12" box can reach 128dB at 33Hz, or 122dB for a single 12". A THAM12 is only 105dB at the same frequency.


Edited by Hemisphere - 02 April 2018 at 3:12pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rbarone Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2018 at 2:52pm
thx hemi - i'm sure it's evident, that my sim & tech knowledge is not a strong suit...  so, all of this help is very much appreciated.  my "expertise" as it is, lies in the fabrication end of things - i'm a musician with a custom cabinet shop.

my apprentice is very savvy with his pc..  i'll put him on it.  i should've thought of that sooner.  thx!
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